The present invention relates to a method and apparatus for presetting an ink roller cleaning speed for automatically setting the current speed of a printing press to a speed preset for ink roller cleaning.
Generally, in a printing press, when the printing color is changed, the ink roller is cleaned. This cleaning operation is performed by setting the speed (rotational speed of the cylinder) of the printing press to a speed appropriate for cleaning, sprinkling a cleaning fluid to several tens of ink rollers, and recovering the waste fluid by a doctor blade set at a predetermined position. In this cleaning operation, if the current speed is higher than the preset speed, the cleaning fluid is scattered around to disable reliable cleaning; if the current speed is lower than the preset speed, the cleaning time is prolonged. Thus, the current speed must be set to a preset speed appropriate for cleaning.
Conventionally, a method is used wherein, upon start of a cleaning operation, the current speed is automatically set to a preset speed appropriate for cleaning in response to a preset switch operation which is done in a high-speed rotation mode among a plurality of rotation modes.
The high-speed rotation mode described above is generally a state of speed within the range of rotational speeds for printing. In the high-speed rotation mode, the current speed can be set to a desired speed in the given range by dial adjustment. The preset speed appropriate for cleaning is determined as one of the states of speed in the high-speed rotation mode.
However, according to this conventional method of presetting the ink roller cleaning speed, the current speed can be automatically set to the preset speed appropriate for cleaning by operating the preset switch only from a high-speed rotation mode having a variable speed. More specifically, a printing press has various speed modes including a low-speed rotation mode and a slow rotation mode, in addition to a high-speed rotation mode. The low-speed rotation mode is a rotation mode for start and end of printing, and its speed is fixed as it is mechanically determined. The slow rotation mode is a rotation mode for printing preparation and printing press warming up, and its speed is also fixed as it is mechanically determined.
Therefore, conventionally, the current speed cannot be automatically set from the low-speed or slow rotation mode having a fixed speed to the preset speed appropriate for cleaning even by operating the preset switch. For this reason, when the cleaning operation is to be performed in the low-speed or slow rotation mode, the printing press must temporarily be set in the high-speed rotation mode, and then the preset switch is operated, resulting in an extra preparation time before start of cleaning. Furthermore, the current rotation mode (slow, low-speed, high-speed) of the printing press must be confirmed and thereafter an operation in accordance with the current rotation mode must be performed, resulting in a cumbersome operation.